The Diagnostic Medical/Behavioral Core B has three main responsibilities: 1. Identification and induction of experimental and control subjects. 2. Administration and analysis of the medical/neurologic examinations and standardized behavioral tests to assure that subjects meet selection criteria as defined for each research Project. 3. Collaborate with Project Pls to relate the diagnostic findings to the experimental findings obtained from Project studies. Potential subjects will be identified from various sources including Pediatric Neurology Clinic at UCSD Medical Center, Pediatric Primary Care Center, Infant Special Care Nursery, and Infant Followup Clinic, all at UCSD Medical Center; the private medical community; community clinics and schools for referral of particular types of children, including those with focal brain lesions and children with developmental language impairment. Normal control subjects will be recruited from these sources, and through the Developmental Subject Pool at the UCSD Department of Psychology. Diagnostic medical/neurologic procedures include the completion of a medical and developmental history and general medical and detailed neurologic examination on each subject. The behavioral test battery was selected for the following reasons. We wanted: 1. Measures that will allow us to test children across a range of ages. 2. Measures that examine a variety of intellectual and cognitive abilities. 3. Measures that can be administered and scored relatively quickly so that subject inclusion decisions can be made in a timely fashion. 4. Measures that are better suited or can be adapted for impaired children. Finally, in addition to subject identification, induction and screening, Core investigators will collaborate with Project P.I.'s in analyzing relationships between the diagnostic findings and experimental findings obtained from Project studies.